The optimal chain length for kidney paired exchanges: an analysis of the Dutch program.

Living donor kidney exchange programs offer incompatible donor-recipient pairs the opportunity to be transplanted. To increase the number of these transplants, we examined in our actual donor-recipient couples how to reach the maximum number of matches by using different chain lengths. We performed 20 match procedures in which we constructed four different chain lengths: two, up to three, up to four and unlimited. The actual inflow and outflow of donor-recipient couples for each run were taken into consideration in this analysis. The total number of matched pairs increased from 148 pairs for only two-way exchanges to 168 for three-way exchanges. When a chain length of 4 was allowed five extra couples could be matched over a period of 5 years. Unlimited chain length did not significantly affect the results. The optimal chain length for living donor kidney exchange programs is 3. Longer chains with their inherent logistic burden do not lead to significantly more transplants.